Astrophytum myriostigma (Bishop's Cap)The name Astrophytum comes from the Greek word for star plant. These beautiful plants are globe shaped and are speckled with white scales and flecks. As it ages, the plant becomes columnar.

Origin and Habitat: Highlands of central and northern Mexico (states of Nuevo León, San Luis Potosí and Tamaulipas).Altitude: It grows at elevations ranging from 750 to 1500 metres above sea level.Habitat and Ecology: It grows on stony, calcareous soils on scrubby alluvial plains on steep, east or west (and southwest) facing slopes, and prefers low densities. It is also found in thin layers in the foothills of mountain ranges. Its distribution is limited by its need for stony, calcareous or lime soils. This calcicole also needs carbonates to integrate calcium and make itself more rigid. This species is found in habitat dominated by Agave lecheguilla, which acts as the main nurse plant to A. myriostigma. This species has a wide range and is extremely abundant, but extraction of individuals from natural populations and destruction of habitat from mining activities can threat the species. The habitat is also overgrazed by livestock (goats and cattle), and some subpopulations have been impacted by the building of roads. The same area harbour a rich succulent flora comprising: Gymnocactus viereckii, Neolloydia conoidea, Mammillaria candida, Mammillaria klissingiana, Obregonia denegrii, Thelocactus hexaedrophorus, Turbinicarpus lophophoroides, Ariocarpus retusus, Coryphantha maiz-tablasensis, Ferocactus echidne, Echinocereus blanckii, Echinocactus ingens and Opuntia microdasys.

Description:Astrophytum myriostigma (many dotted) is a spineless succulent plant, usually solitary or with very few basal branches. A transverse section of the stem reveal a perfect star shaped form (like the common star-fish) giving the plant the appearance of a bishop's mitre (hence the common name Bishop's cap)Stem: Globular to cylindric up to 60(-100) cm tall (but occasionally up 150 cm tall) and 10-20 cm in diameter, bright green, covered with many minute white hairy scales that give it a characteristic chalk-white or silvery-grey appearance, but sometime naked. The scales are composed of very fine interwoven hairs, which, under a microscope, are very pretty object.Roots: Fine, fibrous.Areoles: Closed togetherSpines: Wanting.Ribs: Usually 5, sometimes 4(or 3) that increase to eight or more with age ( rarely even 10), vertical, regular, deep, prominent, very broad and acute.Flowers: Funnelform, 4-7 cm long glossy yellow and sweet scented from the areole at the tip of the stem on mature plant. Outer perianth segments narrow, with brown scarious tips. Inner perianth segments numerous, oblong yellow with a silky shine. Scales on ovary tube scaroious, imbricated, very narrow often bristly tipped, with long wool in their axil.Blooming season: A. myriostigma seems to flower independently of day length, flowering asynchronously and intermittently throughout the warm months from the end of winter to the start of autumn. Plants may take up to six years to flower.Fruit: 2-2,5 cm in diameter, greenish to tannish-red, covered with brown, overlapping scales, with long wool in their axil.Seeds: Dark brown, helmet-shaped, shining, with a large depressed hilum, the margins being turned in.

Subspecies, varieties, forms and cultivars of plants belonging to the Astrophytum myriostigma group

Astrophytum myriostigmaLem.: It is a spineless solitary plant covered with many white dots. A transverse section of the stem reveal a perfect 5 pointed star shaped form (like the common star-fish) giving the plant the appearance of a bishop's mitre (hence the common name Bishop's cap)

Astrophytum myriostigma f. proliferumhort.: has an abnormal tendency to branch forming small side pups from the areole. In cultivation there are several clones some of them branching like mad, while other almost normal.

Astrophytum myriostigma cv. Hakujo Fukuryu: has inherited by 'cv. Fukuryu' the felty line between contiguous areoles and by 'cv. Fukuryu' the many irregular (more or less prominent) “warts” between and on the ribs.

Astrophytum myriostigma cv. Hakujo Hakuun: has inherited by 'cv. Fukuryu' the felty line between contiguous areoles and by 'cv. Hakuun' the many irregular white flecks that condense forming characteristic cloud-like patches.

Astrophytum myriostigma cv. HanakagoTony Sato: In Japan The name “hanakago” also refers to Aztekium ritteri. It is a nude plant with a wrinkled appearance, almost "crumpled" recalling an extreme form of cv. Fukuryu.

Astrophytum myriostigma cv. Huboki: The stems and lateral branches are finger like1,5-2,5 cm in diameter, up to12 cm tall. it has white dots that condense at evenly-spaced intervals on the epidermis forming a cloud like decorative design.

Astrophytum myriostigma cv. Koh-yo: (koo-yo or kôyo) has bright yellow and red stem that gradually turn to dark green. The colouring accentuates on winter and each individual plant has its own unique particular colouration.

Astrophytum myriostigma cv. OnzukaTony Sato: (In Japanese speaking "Onzuka Ranpo-gyoku") has snowy-white, heavily speckled epidermis with fabulous markings much like the ‘kabuto’ asterias. The white marking varies considerably from plant to plant and there exist an enormous number of different designs.

Astrophytum myriostigma cv. Sazanami: has characteristic wave designs or embroidery patterns on the ribs, so it seems like the woolly areoles are connected with each other by small embroidered ripples.

Astrophytum myriostigma cv. Yoroi: (In Japanese speaking Yoroi kikko herikan) has prominent pointed tubercles along the ribs like "Kikko" and the irregular (more or less prominent) supplemental ribs between and on the ribs surface like "Fukuryiu".

The fruit of A. myriostigma (above) is very hairy, dehisces apically and has a greenish inner colour.Photo by: Valentino Vallicelli

The fruit of A. coahuilense it is very different, pinkish coloured and opens basally.Photo by: Valentino Vallicelli

The ribs varies from 3 to (usually) 5Photo by: Valentino Vallicelli

In older plants the areoles are large and woolly, often brownish/reddish,but also white/yellowish to tan/black.Photo by: Cactus Art

Astrophytum myriostigmaPhoto by: Alexander Arzberger

Astrophytum myriostigmaPhoto by: Cactus Art

Cultivation and Propagation: Astrophytum myriostigma is a summer grower species relatively easy to grow. It is sometime seen as a grafted plant but grows very well on its own roots too.Growth rate: It is a slow growing and easily flowering species.Soil: Use mineral well permeable substratum with little organic matter (peat, humus), plants may become too elongated if compost is too rich.Repotting: Re-pot every 2 years. Use pot with good drainage.Fertilization: It grows much faster with a low nitrogen content fertilizer in spring and summer. Potassium helps maintaining the plants compact and healthy. Watering: Requires careful watering to keep plant compact. Water sparingly from March till October, the thin, fibrous roots suffer if there is humidity, therefore the plant should be watered only when the surrounding terrain is dry. Keep dry as soon as the temperature starts dropping in October and keep it perfectly dry in winter at temperatures from 5 to 15 degrees centigrade.Hardiness: They need to be kept in a cool place during winter rest and are somewhat resistant to frost if kept on the dry side prior to, and during, cold weather (due to the altitude they are hardy to -5 C ° C, or less for short periods). Although it is one of the easier Astrophytum to grow, it tends to rot in winter during the resting phase, if kept wet. In the rest period no high atmospheric humidity!!Sun Exposure: Light shade to full sun, its colour tends to richer and darker when grown in light shade.Uses: It is an excellent plant for container growing. It always looks good and stays small. Pests & diseases: It may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, there are several pests to watch for: - Red spiders: Red spiders may be effectively rubbed up by watering the infested plants from above.- Mealy bugs: Mealy bugs occasionally develop aerial into the new growth among the wool with disfiguring results, but the worst types develop underground on the roots and are invisible except by their effects. - Scales: Scales are rarely a problem. - Rot: Rot is only a minor problem with cacti if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much. To prevent rottenness it is also advisable to surround its root neck by very rough sand or grit, this help a fast water drainage.Propagation: Almost exclusively by seed. Plants are sometimes grafted onto column-shaped cacti. Cutting scions from a flourishing plant is almost a crime because the scions do not root easily.Remarks: This quite variable plant has been widely grown for years and is now available in several cultivated variety and several breeds do exist. The famouse “Onzuka” is only one of these and though maybe the most beautiful, but a lot of other forms are represented in many collections.